9 month old nightmare is it just separation anxiety?

[Reecesmummy140111]

Our 9 month old has been sleepin perfectly thru the nite since two n half months in his own room but lately he wont have any of it. he wakes in the night screamin uncontrollably. he has been teething but make sure the painkillers are in his system so it shouldnt be that. once we console him if i go to put him bak in his cot he starts again. i've moved cot bak into our room n removed the mobile incase it that that was the problem. the first night he slept all thru not a peep but since everynite he starts to the point where he will onli settle if hes in the bed with us. I'm against this as i dont want him relying on that. also when he stay at his nans in the travel cot he sleeps all thru not a murmur. i've tried leavin him to cry but it doesnt do anythin he just crys harder. I propb dont help things cus he falls to sleep in ma arms everynite. please help!!!